1. Field of the Invention
The present invention relates to a pump, especially to a pneumatic dual partition membrane pump with a design of separated pump body and external pneumatic control valve. Moreover, the present invention further provides an external pneumatic control valve used in a pneumatic dual partition membrane pump.
2. Description of Related Art
A pump is a device for conveying or moving liquid, gas or special fluid medium, i.e. a machinery performing work to the fluid. The category of pump is complicated, if sorted by the means of applying pressure to fluid, pumps can be categorized into three types which are displacement pump, dynamic pump and electromagnetic pump. The displacement pump includes a reciprocal pump and rotation pump (rotor pump), the convey means is high pressure with small flow amount. The dynamic pump includes a centrifugal pump and vortex pump, the convey means is low pressure with large flow amount. The electromagnetic pump can be used to convey liquid conductive member.
For an electronic factory, for example a semiconductor fab processing etching to the wafer, strong acid or alkaline liquids are often used. However, there is a concern of polluting the liquid due to the cavitation or acid erosion occurred at the location where the blade wheel of dynamic pump is installed. As such, manufacturers in the relative arts have developed a pneumatic dual partition membrane pump totally made of an acid and alkaline resistant material, such as polytetrafluoroethylene (PTFE), for preventing the pump being eroded by the acid or alkaline liquid.
The above-mentioned pneumatic dual partition membrane pump is a displacement pump, in which a pump body is installed with a pressure control valve. The pneumatic dual partition membrane pump mainly utilizes the pressure control valve to drive a main shaft capable of reciprocally moving in the pump body, two side of the main shaft are installed full covered type partition membranes, each partition membrane divides two pump chambers into an air room and a liquid room which are independent from each other. When the high pressure air is supplied into a pump, the pressure control valve is enabled to operate and the main shaft is driven to reciprocally move, thus the two partition membranes are flexurally deformed at the same time to change the volume of each liquid room, thereby sucking in or pumping out liquid via the pressure difference.
With the reciprocal flexural deformation, the partition membrane may break due to elastic fatigue, therefore the partition membrane is seen as a consumable component due to the needs of replacement. What shall be addressed is that when the partition membrane breaks, the strong acid or alkaline liquid remained in the liquid room may flow along the internal pipeline and enter the pneumatic control valve, so the airtight component in the pneumatic control valve such as an O ring may be eroded, thus not only the liquid is polluted, the airtight effect of the pneumatic control valve may be damaged, and the whole set of pneumatic control valve has to be replaced. So for users, the costly replacement of pneumatic control valve is a disadvantage which shall be improved.